Lint: Silence few given goconst lint warnings

While we have these string literals on repeated on multiple places in the
library, I cannot see real tangible benefit extracting these to constants
considering following facts:
 (1) while 'unknown' or 'host' are repeated, they are often times used in
     different context and thus perhaps worth extra const per each use.
 (2) while these string literals repeat, the library is full of string literals
     with special meaning that should be made constants too
 (3) readability would suffer

Signed-off-by: Šimon Lukašík <slukasik@redhat.com>

.tool/lint

@@ -41,6 +41,7 @@ ${LINTER} \
 	--exclude='duplicate of.*_test.go.*\(dupl\)$'\
 	--exclude='cmd\/client\/.*\.go.*\(dupl\)$'\
 	--exclude='libpod\/.*_easyjson.go:.*'\
+	--exclude='.* other occurrence\(s\) of "(container|host|tmpfs|unknown)" found in: .*\(goconst\)$'\
 	--exclude='vendor\/.*'\
 	--exclude='podman\/.*'\
 	--exclude='server\/seccomp\/.*\.go.*$'\